1. Field of the Invention
The present invention relates in general to the biotechnology field and, in particular, to a protein crystallography hanging drop multiwell plate and methods for fabricating and using the protein crystallography hanging drop multiwell plate.
2. Description of Related Art
Today biochemical studies associated with growing protein crystals and other biological crystals are carried out on a large scale in both industry and academia. As such, it is desirable to have an apparatus that allows researchers to perform these studies in a convenient and inexpensive fashion. Because they are relatively easy to handle and low in cost, multiwell plates are often used in these studies. And, if the study involves growing protein crystals via a hanging drop vapor diffusion process, then the wells of a multiwell plate are often covered with slides or a lid having one or more drops of a protein solution and a reagent solution hanging therefrom which turn into the protein crystals. In particular, the drops hanging from the bottom side of the slides or lid turn into protein crystals by interacting via a vapor diffusion process with a higher concentrated reagent solution located within each well of the multiwell plate. However, the traditional slides or lid used to grow protein crystals in this manner have several drawbacks which are described in greater detail below with reference to FIGS. 1–3.
Referring to FIGS. 1A–1B (PRIOR ART), there are illustrated different views of one set of traditional slides 100 designed to cover the wells 104 in a multiwell plate 102. Each slide 100 typically has a circular shape and is sized to fit over one of the wells 104 in the multiwell plate 102. And, each well 104 includes a rim 106, sidewalls 108 and a bottom 110 (see FIG. 1B). The wells 104 are generally arranged in a matrix of mutually perpendicular rows and columns. For example, the multiwell plate 102 can include a matrix of wells 104 having dimensions of 4×6 (24 wells), 8×12 (96 wells) and 16×24 (384 wells). The multiwell plate 102 shown includes an array of ninety-six wells 104.
To grow a protein crystal on the bottom side of one slide 100, the researcher applies a bead of grease 112 (e.g., high vacuum grease) along the rim 106 of one of the wells 104. Typically, the researcher would leave a small opening such as 2 mm between the start and end of the bead of grease 112. The researcher then pipets a small amount (e.g., 1.0 millimeter) of a reagent solution 114 into the well 104. One or more drops 116 (only one shown) including a small amount of a protein sample (e.g., 1.0 microliter) and a small amount of a reagent solution (1.0 microliter) that can be taken from the well 104 are then pipetted onto a bottom side of the slide 100. Thereafter, the researcher inverts the slide 100 so that the drop 116 is hanging down from the slide 100 and then positions and places the slide 100 onto the grease 112 around the well 104. To relieve the air pressure within the well 104, the researcher presses the slide 100 down onto the grease 112 and twists the slide 100 to close the small opening in the grease 112. This process is then completed for each well 104 in the multiwell plate 102. Unfortunately, there are a number of disadvantages associated with using the slides 100 and the multiwell plate 102. First, the researcher must work with messy grease 112 and possibly spend a lot of time applying the grease 112 to the rims 106 of each well 104. Secondly, the researcher must work with and handle a large number of relatively small slides 100 to utilize all of the wells 104 in the multiwell plate 102. Thirdly, the slides 100 and the grease 112 are expensive.
Referring to FIGS. 2A–2B (PRIOR ART), there are illustrated different views of another set of traditional slides 200 designed to cover the wells 204 in a multiwell plate 202. Each slide 200 typically has a circular shape and is sized to be placed on a ledge 203 in one of the wells 204 in the multiwell plate 202. And, each well 204 includes a rim 206, sidewalls 208 and a bottom 210. The wells 204 are generally arranged in a matrix of mutually perpendicular rows and columns. For example, the multiwell plate 202 can include a matrix of wells 204 having dimensions of 4×6 (24 wells), 8×12 (96 wells) and 16×24 (384 wells). The multiwell plate 202 shown includes an array of ninety-six wells 204.
To grow a protein crystal on the bottom side of one slide 200, the researcher pipets a small amount (e.g., 1.0 millimeter) of a reagent solution 214 into the well 204. One or more drops 216 (only one shown) including a small amount of a protein sample (e.g., 1.0 microliter) and a small amount of a reagent solution (1.0 microliter) that can be taken from the well 204 are then pipetted onto a bottom side of the slide 200. Thereafter, the researcher inverts the slide 200 so that the drop 216 is hanging down from the slide 200 and then positions and places the slide 200 onto the ledge 203 within the well 204. After, this process is completed for each well 204 in the multiwell plate 202, then the researcher places one or more strips of tape 218 (only shown in FIG. 2B) over the top of multiwell plate 202. Unfortunately, there are a number of disadvantages associated with using the slides 200 and the multiwell plate 202. First, the researcher must work with and handle a large number of relatively small slides 200 to utilize all of the wells 204 in the multiwell plate 202. Secondly, the researcher must cut the tape 218 in order to have access to anyone of the slides 200 located within a particular well 204. Thirdly, the slides 200 are expensive.
Referring to FIGS. 3A–3B (PRIOR ART), there are illustrated different views of a traditional lid 300 designed to cover the wells 312 in a multiwell plate 302. The lid 300 includes a rigid frame 304 that supports a filter membrane 306 on which there is placed a hydrophobic mask 308 all of which are protected by a removable cover 310 (see exploded view in FIG. 3B). The lid 300 is sized to fit over all of the wells 312 in the multiwell plate 302. And, each well 312 includes a rim 314, sidewalls 316 and a bottom 318. The wells 312 are generally arranged in a matrix of mutually perpendicular rows and columns. For example, the multiwell plate 302 can include a matrix of wells 312 having dimensions of 4×6 (24 wells), 8×12 (96 wells) and 16×24 (384 wells). The multiwell plate 302 shown includes an array of ninety-six wells 312.
To grow a group of protein crystals on top of the hydrophobic mask 308 of the lid 300, the researcher applies a bead of grease 320 (e.g., high vacuum grease) on the rims 314 of the wells 312 in the event the wells 312 are not pre-greased. The researcher then pipets a small amount (e.g., 1.0 millimeter) of a reagent solution 322 into each well 312. One or more drops 324 (eight drops 324 are shown) including a small amount of a protein sample (e.g., 1.0 microliter) and a small amount of a reagent solution (1.0 microliter) that can be taken from the well 104 are then pipetted onto the hydrophobic mask 308 of the lid 300. Thereafter, the researcher positions the lid 300 over the multiwell plate 302 and then pushes the lid 300 down onto the grease 322 located around each well 312. The lid 300 can have holes 326 formed in the frame 304. And, the multiwell plate 302 can have pins 328 extending up therefrom which fit into the holes 326 in the frame 304 to assure that the lid 300 is properly aligned with the multiwell plate 302. Unfortunately, there are a number of disadvantages associated with using the lid 300 and the multiwell plate 302. First, the researcher must work with messy grease 320 and possibly spend a lot of time applying the grease 320 to the rims 314 of the wells 312. Secondly, the filter membrane 306 and hydrophobic mask 308 of the lid 300 are very fragile and can easily break. Thirdly, the lid 300 is very expensive. Finally, the lid must be flipped after crystallization in order to harvest the crystals.
Accordingly, there is and has been a need for a cost effective and user-friendly multiwell plate that integrates features of the lids, without requiring the lid and the accompanying drawbacks associated with their use. This need and other needs are satisfied by the multiwell plate and the methods of the present invention.